title: Synthesis, photophysics and nonlinear optical properties of stilbenoid pyrimidine-based dyes bearing methylenepyran donor groups.
abstract: The nonlinear properties and the photophysical behavior of two π-conjugated chromophores that incorporate an electron-deficient pyrimidine core (A) and γ-methylenepyrans as terminal donor (D) groups have been thoroughly investigated. Both dipolar and quadrupolar branching strategies are explored and rationalized on the basis of the Frenkel exciton model. Even though a cooperative effect is clearly observed if the dimensionality is increased, the nonlinear optical (NLO) response of this series is moderate if one considers the nature of the D/A couple and the size of the chromophores (as measured by the number of π electrons). This effect was attributed to a disruption in the electronic conjugation within the dyes' scaffold for which the geometry deviates from planarity owing to a noticeable twisting of the pyranylidene end-groups. This latter structural parameter also has a strong influence on the excited-state dynamics, which leads to a very efficient fluorescence quenching.
authors.affiliation: Institut des Sciences Chimiques de Rennes, UMR CNRS 6226, IUT de Lannion, rue Edouard Branly, BP 30219, 22302 Lannion Cedex, France. sylvain.achelle@univ-rennes1.fr
authors.forename: Sylvain
authors.initials: S
authors.lastname: Achelle
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Malval
authors.forename: Stéphane
authors.initials: S
authors.lastname: Aloïse
authors.forename: Alberto
authors.initials: A
authors.lastname: Barsella
authors.forename: Arnaud
authors.initials: A
authors.lastname: Spangenberg
authors.forename: Loic
authors.initials: L
authors.lastname: Mager
authors.forename: Huriye
authors.initials: H
authors.lastname: Akdas-Kilig
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Fillaut
authors.forename: Bertrand
authors.initials: B
authors.lastname: Caro
authors.forename: Françoise
authors.initials: F
authors.lastname: Robin-le Guen
mesh_terms: D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry; D007700:Kinetics; D008968:Molecular Conformation; D011714:Pyrans / Q000737:chemistry*; D011743:Pyrimidines / Q000737:chemistry*; D011789:Quantum Theory; D013056:Spectrophotometry, Ultraviolet
chemical_list: D005456:Fluorescent Dyes; D011714:Pyrans; D011743:Pyrimidines; C030986:pyrimidine
keywords: chromophores; conjugation; heterocycles; nonlinear optics; photophysics